Instead of taking over his family's farm in Norrøngard, Karn would rather play the board game Thrones and Bones, until half-human, half-frost giantess Thianna appears and a family crisis sends them on an adventure, chased by a dragon, undead warriors, an evil uncle, wyverns, and various trolls and giants.

Karn Korlundsson must travel to the faraway city of Castlebriar, learn to play a new board game called Charioteers, decipher the Riddle of the Horn, and tangle with mysterious elves in order to rescue his best friend, Thianna Frostborn, facing great dangers at every step. Includes directions for playing Charioteers.